The entire disclosure of Japanese Patent Application No. 2000-214340 filed on Jul. 14, 2000, including specification, claims and summary is incorporated by reference in its entirety.
1. Field of the Invention
The present invention relates to a hoist apparatus and, more particularly, to a compact and small-sized hoist apparatus for hoisting an object, having a control unit disposed discretely and independently from a hoist body member and at a position close to and on the side of a lower hook member that hoists an object.
2. Description of the Related Art
There are various types of hoist apparatuses. A hoist apparatus of one type is a small-sized hoist machine having a hoist body member with a drum rotatable in both normal and opposite directions disposed therein and with a lower hook member for hooking and hoisting objects mounted on the bottom end thereof. A wire for raising or lowering objects is configured such that its top end is secured to the hoist body member at a predetermined position and its bottom end is connected to the drum so as to be wound up around the drum and wound down as the drum rotates. A control unit for controlling the rotational drive of the drum is disposed in the hoist body member.
As this hoist machine has the lower hook member for hooking and hoisting or releasing objects mounted on the hoist body member, the lower hook member is lowered together with the hoist body member by operating the control unit and winding the wire down. After the objects have been hooked and hoisted by the lower hook member or released therefrom, the lower hook member is raised together with the hoist body member by winding the wire up by means of the operation of the control unit. Once the lower hook member is raised to a predetermined position, then it may be transferred horizontally to a predetermined location and lowered by winding the wire down to a desired position for releasing or hooking and hoisting objects.
For this type of the hoist machine, the control unit is raised and lowered together with the lower hook member for hoisting objects so that this hoist machine is suitable for manual operation by the control unit within reach of an operator. Moreover, the lower hook member is disposed in the position close to the control unit so that even the manual operation for hooking or releasing objects can be carried out readily by raising or lowering the wire for hooking the objects. Therefore, this type of the hoist apparatus is particularly suitable for the operation of hoisting and transferring lightweight objects to a predetermined location.
This type of the hoist machine has the shortcomings, however, in that it uses a wire and the wire has to be exchanged at a relatively short interval due to its shorter life. Further, the hoist body member has to be disassembled for exchanges of wires. This renders the maintenance of the hoist machine difficult and laborious.
Moreover, the wire for use with this type of the hoist machine has to be short due to a small wire container in which the wire is wound and accommodated, so that the lift distance of the wire has to become so short. For this type of the hoist machine, the lift distance of the wire may be, for example, as short as about 2meters. In addition, the wire is wound around the drum in a form of plural loops such that an outer loop of the wire wound around the drum is wound and superimposed over an inner loop thereof. This configuration varies the speed of winding the wire up or down with the number of loops of the wire. In other words, the inner loop of the wire can be wound up faster than the outer loop thereof and the outer loop of the wound wire can be released faster than the inner loop thereof. This renders the operation of the hoist machine inconvenient because the wound wire cannot be lifted or lowered at a constant speed and the adjustment of the winding speed is rendered laborious and complicated in the operation of the hoist machine itself.
This conventional hoist machine has the lower hook member directly fixed on the hoist body member or arranged so as to swing in one direction only. Therefore, the lower hook member has to be swung in one direction or in another direction in order to allow the lower hook member to adapt to an eyebolt or other fixed-type hoisting jig and to hook it and hoist objects. Moreover, the lower hook member has to be operated together with the hoist body member so that this operation is very laborious and causes risk. This further renders the operability of the hoist apparatus poor as a whole.
In addition, for the hoist machine of this conventional type, the control unit is mounted integrally on the hoist body member so as to render the operation of the control unit easy by one hand, yet difficult and inconvenient for the operation when the operator has to manipulate it by the other hand. Furthermore, an exhaust outlet for gases from a pneumatic motor is generally disposed in the position close to the operator. This is hazardous to the health of the operator. Moreover, the close location of the exhaust outlet to the operator gives very noisy working conditions for the operator.
Therefore, the present invention has the object to solve the shortcomings of the conventional hoist machines and to achieve improvements in such conventional hoist machines as described above.
It is another object of the present invention to provide a hoist apparatus that can readily be operated so as for a hook member to hoist an object.
It is a further object of the present invention to provide a hoist apparatus that can readily be operated by an operator without paying much attention to the operator""s location.
In order to achieve the objects, the present invention in a major aspect provides a hoist apparatus for hoisting an object, which includes a hoist body member having a pneumatic motor and a chain-winding wheel member such as a chain engagement member rotatable by the pneumatic motor, a chain having a top end and a bottom end for hoisting an object, the chain being wound up or down at a top end portion by the chain-winding wheel member rotated by the pneumatic motor to raise or lower the object to a predetermined position, a lower hook member for hooking and hoisting the object, the lower hook member being secured to the bottom end of the chain, and a control unit for driving or suspending the operation of the pneumatic motor; wherein the control unit is detachably connected to the chain at the position apart from the hoist body member and close to the lower hook member; and wherein a distance of the chain between the control unit and the lower hook member is set to be variable.
In a preferred embodiment of the present invention, the control unit for the hoist apparatus is disposed discretely and independently from the hoist body member and fixed to the chain so as to be movable around the chain. This embodiment provides the advantage that the control unit can be turned in a different direction so as to fail to interfere with the hooking of the object by the lower hook member, otherwise the position of the control unit would block the operation of the lower hook member for hooking the object or it would interfere with the operator""s position upon operating the control unit for hooking or releasing the object.
In another preferred embodiment of the present invention, the control unit is provided with the operational switch through which the operator can turn the pneumatic motor on or off by one hand. In another preferred embodiment of the present invention, the control unit is arranged so as to shift the position in which its operational switch is located. That the position of the operational switch can be shifted so as to adapt to the position of an operator""s preference can provide the operator with the readiness for operating the hoist apparatus.
In a further preferred embodiment, the control unit is composed of a chain-raising lever and a chain-lowering lever so that the direction of winding the chain can be quickly changed simply by shifting the lever""s operation. In a still further preferred embodiment, the hoist apparatus of this invention can readily change the direction of winding the chain by the simple operation of depressing the lever.
Other objects, features and advantages will become apparent in the course of the description with reference to the accompanying drawings.